Amplifier has fuse blown (proberbly caused by playing music to loud at aux, from mp3-player). I see no damaged transistors or elco, but when replacing fuse, it will blow up right away.
What could be the Problem, or what components should I replace more?
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Re: Denon PMA 520 fuse blown
Check that you are replacing the fuse with the correct type first. Fuses marked with a T following the rating are "slo blo" fuses and if a fast blow is used instead, it will fail again at turn on. Otherwise, the amp will have a fault occurring, probably in the output stages. You should refer this type of fault to a repair guy that knows HiFi. as this sort of repair needs an experienced touch.
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It could be the amplifier but most likely it’s going to be either the connections or a power supply issue. Do you have anything plugged into the same outlet? What type of power strip are you using. The amp will usually go into a protect mode as to not damage anything before it would create the environment to cause a blown speaker. I know that with your model, along with multiple others, have had issues with the power board needing replacement.
speaker outputs should NEVER be subjected to DC voltages, chances are that you've blown the output transistors.
your options are limited, if you're lucky it'll have a separate low-level amplifier to the headphone jack (if it has one) you could use as an AUX output to an external amplifier.... or take it apart and find the output transistors to reference and replace, or bypass those altogether with a Class-D amplifier.... dependent on your level of tinkering skills of course.
maybe because your amp is overload, try to load 8 ohms single speaker per channel, then try to playing loud, if blown your amp again, the power transistors bias maybe excess to 0.6V ' if transistorized, if IC power amp, check cooling fan.
It is likely one of the amps have blown as well as the power supply. The pwoer supply wipes out about $30 of components when it goes. If the fuse had been replaced after initial failure this results in more damage. For the power supply, typically the two IGBT's are wiped out and the four transistors driving them as well as the regulator chip and one or more of the gate speedup diodes which are surface mounted. Sometimes the surge limit resistors which are ceramic pacakged are blown. The hardest part is removing the heatsinks with the IGBT's on them. You DO need a desoldering station to work on this.
Usually you will find damage to the rearmost amp in the amplifier module. An arc beween layers of the multilayer circuit board causes inital failure. Three MOSFET transistors are blown and a Zener plus the board is charred and this cancer has to be ground away and re-insulated and circuit traces replaced by jumpers. Sometime the .03 ohm metering resistor on the bottom is fried... when that happens, two small surface mounted transistors are blown as well. All in all $50 of components are damaged typically.
You did a lot of damage, and replacing the fuse and trying it has caused much more.
There will be about seven blown parts on the amp and a dozen on the power supply. To give you an idea of the extent, the WHOLESALE parts cost is roughly $50, including the main power supply switchers IGBT's which cost nearly $20 for the pair by themselves.
I have repaired several of these and the larger cousin the PMP5000. It is a lot of skilled work to repair these.
The cause is a marginal insulation between layers of the multi-layer amplifier board. Usually the rearmost amp arcs between the layers. This fries three big switching transistors followed sometimes by a metering resistor and two small surface mounted transistors. A zener diode often goes. The cancer and burned area has to be ground out with a dental drill and new wire replaces the blown circuit traces.
If you are under warranty, take the unit for replacement.
The thing that can arc the amp is if speaker leads are marginal or get pulled out while under power. Excessive volume, especially pulses at high level can break down the insulaton causing the arc and failure. The black smoke is likely from the metering resistor.
you probably have a short in the circuit some where. you need to replace the transistor and look at all the solder joints to make sure there not damaged or cracked. i have the same amplifier and i replaced the fuse several times and it blew every time up until the last time when the 4 of the power output transistors blew. what ever you do do not try and power it on till you do all the things i told you or you will have sparks and fire. my mistake cost me my amplifier. but might help you get yours repaired
The reason why fuses blow is that the current is too much. Is the fuse rating according to the specs ? If yes then ...
One or more output power transistor (or audio power IC) may be shorted.
have it checked before replacing another fuse as this might cause more damage.
what was your amp? ic or transistorized? the output transistor of your amp may be opened, mostly it will short but because u still hear sound, maybe open and only the driver transistor are working. replacing output transistor or IC could solve the problem.